Give the polyurethane rings a quick stretch by hand before installing them. You should be able to get the same sensitivity from your slings as you get with rubber rings. Consult the game manual for rings sizes as getting the correct size is more critical with urethane vs. soft white rubber.

Give them a quick stretch, position yourself behind the flipper bat, put the Super-Band over the shaft end of the flipper bat (The wide end), and push it over the front of the bat with both thumbs. Good thing is they outlast any other flipper material and don't need changed often.